On Fri, Feb 26, 2021 at 02:31:31PM +0100, Heiner Kallweit wrote: > On 26.02.2021 13:18, Kai-Heng Feng wrote: > > On Fri, Feb 26, 2021 at 8:10 PM Heiner Kallweit <hkallwe...@gmail.com> > > wrote: > >> > >> On 26.02.2021 08:12, Kalle Valo wrote: > >>> Kai-Heng Feng <kai.heng.f...@canonical.com> writes: > >>> > >>>> Now we have a generic D3 shutdown quirk, so convert the original > >>>> approach to a PCI quirk. > >>>> > >>>> Signed-off-by: Kai-Heng Feng <kai.heng.f...@canonical.com> > >>>> --- > >>>> drivers/net/wireless/realtek/rtw88/pci.c | 2 -- > >>>> drivers/pci/quirks.c | 6 ++++++ > >>>> 2 files changed, 6 insertions(+), 2 deletions(-) > >>> > >>> It would have been nice to CC linux-wireless also on patches 1-2. I only > >>> saw patch 3 and had to search the rest of patches from lkml. > >>> > >>> I assume this goes via the PCI tree so: > >>> > >>> Acked-by: Kalle Valo <kv...@codeaurora.org> > >> > >> To me it looks odd to (mis-)use the quirk mechanism to set a device > >> to D3cold on shutdown. As I see it the quirk mechanism is used to work > >> around certain device misbehavior. And setting a device to a D3 > >> state on shutdown is a normal activity, and the shutdown() callback > >> seems to be a good place for it. > >> I miss an explanation what the actual benefit of the change is. > > > > To make putting device to D3 more generic, as there are more than one > > device need the quirk. > > > > Here's the discussion: > > https://lore.kernel.org/linux-usb/00de6927-3fa6-a9a3-2d65-2b4d4e8f0...@linux.intel.com/ > > > > Thanks for the link. For the AMD USB use case I don't have a strong opinion, > what's considered the better option may be a question of personal taste. > For rtw88 however I'd still consider it over-engineering to replace a simple > call to pci_set_power_state() with a PCI quirk. > I may be biased here because I find it sometimes bothering if I want to > look up how a device is handled and in addition to checking the respective > driver I also have to grep through quirks.c whether there's any special > handling.
I haven't looked at these patches carefully, but in general, I agree that quirks should be used to work around hardware defects in the device. If the device behaves correctly per spec, we should use a different mechanism so the code remains generic and all devices get the benefit. If we do add quirks, the commit log should explain what the device defect is. Bjorn
